A national survey of the Oral Health of School Children was conducted during the 1986-87 school year. Approximately 41,000 children were examined by 13 trained and calibrated dental teams. When compared to a similar survey conducted in 1979-80, DMFS had declined 37%. Mean DMFS was lower in all regions of the country; however, there were still regional variations as before. Approximately 50% of the children aged 5-17 were caries free in their permanent dentition. A monograph on caries status, "Oral Health of U.S. Children, 1986-87," was published. Mean caries experience for primary teeth for children aged 5-9 years showed a 26% decline from the 1979-80 survey. The dfs was lower in every region except Region VII, with the greatest decline observed in Reg. I. Approximately 50% of the children had no dfs; 28% had more than 4 surfaces d or f. Only 7.6% of the children aged 5-17 had sealants present. The average number of sealants in children with sealants was 4.2 per child. An estimate of the prevalence of dental fluorosis was made using Dean's Index on 2nd through 12th graders. 22% of children showed definite signs of fluorosis, 17% very mild, 4% mild, 1% moderate and 0.3% severe. Microbiological samples of mutans streptococci and Lactobacillus were evaluated in relation to dental caries. Children with mutans counts of zero CFU/ml of salivary rinse had less than half as many DMFS as those with any detectable mutans. The level of caries rose with increases in mutans.